Multi-dimensional sheave for use in tension measurement systems

ABSTRACT

Disclosed is a sheave for use in a tension measurement system to measure a tension force in a cable. The sheave includes a first diameter and a second diameter. The sheave is configured to rotate about an axis to orient the first diameter or the second diameter toward the cable, such that a contact force between the sheave and the cable is measured by a tension sensor to determine the tension force in the cable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/712,613, filed Jul. 31, 2018, entitled “Multi-Dimensional Sheave forUse in Tension Measurement Systems.” The entire content of theabove-referenced application is incorporated herein by reference.

BACKGROUND

Tension measurement systems are employed to measure the tension force ina cable. Conventional systems are equipped with multiple sheaves ofvarying sizes that must be changed to measure the tension force incables of different sizes.

For example, when converting the measurement system from a smallerdiameter cable to larger diameter cable (or vice-versa), three of thelarger sheaves must be removed and replaced with three smaller sheaves.Such a process is time-consuming, and handling multiple sheaves makesthem prone to misplacement, which may lead an operator to use a sheavethat is not sized for the selected cable. The result can be incorrect orinaccurate readings, or damage to the measuring system and/or the cable.

Thus, a tension measurement system that avoids the need for multiplesheaves while proving the flexibility of accurately measuring multiplecables of varying diameters is desirable.

SUMMARY

The present disclosure relates generally to a sheave having multiplediameters. In particular, the sheave is configured for use in a tensionmeasurement system to measure a tension force in cables of differentdiameters.

More particularly, the presently disclosed sheave can eliminate the needto replace sheaves during a measuring operation for multiple cables.Instead, an operator will only need to pull a pin, spin a single sheave,and reinsert the pin in a different position in order to reorient thesheave to present a diameter for accommodating variable cable diameters.Thus, the presently disclosed multiple diameter sheave simplifies andspeeds the procedure for transitioning from small to large cablediameters sheaves, and vice-versa.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIGS. 1-3 illustrate an example multi-diameter sheave, in accordancewith aspects of this disclosure.

FIG. 4 illustrates a tension measurement system employing amulti-diameter sheave as shown in FIGS. 1-3, in accordance with aspectsof this disclosure.

FIGS. 5A-5C illustrate example views of the tension measurement systemof FIG. 4 being deployed, in accordance with aspects of this disclosure.

FIG. 6 illustrates an example tension measurement system engaging acable with a first diameter of a sheave, in accordance with aspects ofthis disclosure.

FIG. 7 illustrates an example tension measurement system engaging acable with a second diameter of a sheave, in accordance with aspects ofthis disclosure.

The figures are not necessarily to scale. Where appropriate, similar oridentical reference numbers are used to refer to similar or identicalcomponents.

DETAILED DESCRIPTION

The present disclosure provides a sheave having multiple diameters. Inparticular, the sheave is configured for use in a tension measurementsystem to measure a tension force in cables of different diameters. Forexample, in order to mate a cable with a corresponding diameter of thesheave, the sheave is configured to rotate about an axis to orient oneof a first diameter or a second diameter toward the cable during ameasurement process. When the tension measuring system applies a contactforce between the sheave and the cable (such as through manipulation ofan adjustable support member or arm), a tension sensor measures atension force in the cable.

The multiple diameters are arranged about the sheave such that a firstarc length spans a first radial position (as measured from within thebody of the sheave), and the second diameter is arranged at a secondradial position spanning a second arc length. Thus, a central channelabout the sheave may have multiple diameters, which can be adjusted andreoriented to accommodate testing of a cable with a particular diameter.Once properly oriented, the sheave can be fixed relative to the cable(e.g., via a fastener, pin, etc.) during a measurement process. Thecable with therefore interface with the sheave, which bears the loadduring a measurement process, the tension on the cable being measureddirectly or indirectly as a result.

Further, the sheave is not limited to two diameters, and may have threeor more diameters about the sheave.

The tension measurement system can include several components tofacilitate the measurement process. For example, the adjustable supportcan be configured to rotate about a fulcrum located on a base to adjustthe position of the sheave. Additionally, a plurality of tensionersconfigured to engage with the cable to provide the contact force betweenthe sheave and the cable when the adjustable support positions thesheave adjacent to the cable.

Thus, as the sheave is arranged between two tensioners along a length ofthe cable, the contact force acting thereon is measured (e.g., via asensor and determined by a measurement unit).

In order to fix the orientation, the sheave may include a first openingthrough which a fastener secures the sheave to the adjustable arm at theaxis. A second opening that is offset from the first opening is designedto accept a removable pin, such that the second opening aligns with afirst or second slot of the adjustable support to orient the first orsecond diameter toward the cable, respectively.

Tension measurement systems are widely used to measure tension in towerand stack guy wires, pretensioned cable barriers, bridges, elevators,winch rope, overhead electric transit wires, fall arrest systems,aircraft cables and utilities cable guardrails, to name but a few. Thesystems are designed to install on a cable, measure the tension, and beremoved quickly. The use of sensitive measurement equipment, includingdigital loadcells, provide a highly accurate reading (e.g., within a 3percent error threshold) without the need for reference to a lookup orcorrection table.

Tension measurement systems are conventionally able to measure tensioncapacities of about 2000 pounds/10 kN/1000 kg 10,000 pounds/45 kN/4500kg, for example. This can be done on cables of varying diameters, suchas 3/16 inch through over 1 inch (i.e. 4.75 mm through 25.4 mm) byemploying a sheave configured to accommodate cables rated for a varietyof sizes.

Despite the many uses of existing tension measuring devices, whenconverting the measurement system from a smaller diameter cable to alarger diameter cable, three of the smaller sheaves must be removed andreplaced with three larger sheaves. Such a process is time-consuming andmultiple sheaves are prone to misplacement, which may lead an operatorto use a sheave that is not sized for the selected cable. The result canbe incorrect or inaccurate readings, or damage to the measuring systemand/or the cable.

By changing the groove diameter, as well as the effective sheave height(e.g. from a standard circular shape to an elongated form) there is noloss of performance during a measurement process. Moreover, although avertical adjustment of the sheave would serve to change the height ofthe sheave relative to the tensioners, without the added accuracyassociated with the change in diameter, errors may remain duringmeasurement, especially with coarse cables.

Therefore, by employing a sheave in a tension measurement system asdisclosed herein, a more robust, versatile, and sensitive system isprovided. Advantageously, the sheave can be applied to various cablewidths, with fewer manufactured parts, fewer and easier configurationchanges, and more accurate measurements.

FIGS. 1-3 illustrate an example sheave 10 having a first diameter 12 anda second diameter 14. The sheave includes a first opening 16 about whichthe sheave is configured to rotate. A second opening 18 is configured toaccept a pin or bolt, which can engage with an adjustable support (see,e.g., FIGS. 4-6). The pin can fix the position of the sheave 10 suchthat the first or second diameter is oriented toward the cable.

As shown in FIG. 2, the first diameter 12 is defined by a radius R1. Forexample, the radius R1 sweeps an arc 20 having a first arc length, asmeasured from a central plane 24 that is perpendicular to an axis ofrotation 26 through the first opening 16. Similarly, the second diameter14 sweeps an arc 22 having a second arc length, as measured from thecentral plane 24.

Thus the first and second diameters form a channel that circles thesheave 10, providing multiple arced grooves upon which a cable can beseated during testing.

Although illustrated as having a first diameter 12 and a second diameter14, three or more diameters may be incorporated into a single sheave.Moreover, sheave 10 is illustrated as having a generally oblong shapewith curved external sides. However, any shape and/or contours may beemployed and capture the benefits of the disclosed sheave. For example,multiple diameters may be machined into a generally circular sheave; agenerally triangular sheave may present three distinct diameters; agenerally square sheave may have four diameters; or any geometrysuitable to rotate about an axis and engage sufficiently with a cableduring a measurement process.

The sheave 10 can be formed of any material of suitable strength forengagement with the cable. For example, metals, carbon compounds,polymers, or combinations thereof may be used to form the sheave 10. Formeasuring tension force in a cable that may be transmitting power,non-conductive materials may be used.

Although illustrated with the first opening 16 being larger than thesecond opening 18, the openings may be of equal size, or the relativesized reversed. Moreover, although illustrated as generally circular,the openings may have any suitable geometry that allows an operator toreorient the sheave to present a desired diameter to the cable.Furthermore, the second opening 18 is illustrated as extending throughthe sheave 10 to accommodate a removable pin. However, additional oralternative methods of fixing the orientation of the disclosed sheaveare available, such as one or more grooves around an edge of the sheave,a slot within the groove through which a pin or other fastener canextend to fix the orientation, among other solutions.

In yet other examples, the adjustable support includes a frame at adistal end extending toward the cable and configured to accept thedisclosed sheave in varying orientations. For example, a generallysquare sheave may fit into a generally square frame. Depending on whichof the four sides is oriented toward the cable, four diameters of thesheave can be available for a measurement process.

FIG. 4 illustrates an example tension measurement system to measure atension force in a cable employing the sheave 10 of FIGS. 1-3. Thesystem includes a base 32 upon which one or more tensioners 30 and/or anadjustable support or arm 36 are attached. The adjustable support 36 isconfigured to rotate about a fulcrum 38 and may include a handle 40 toprovide leverage for an operator during deployment of the system. Insome examples, the handle 40 includes a telescoping pole to improveleverage during a measurement process.

A measurement unit 34 is in communication with one or more sensors, andconfigured to generate a signal associated with a measured value (e.g.,for display 35, to provide an audible alert, for transmission to aremote computing platform, etc.). The measurement unit 34 may include aprocessor configured to parse analog or digital signals from the one ormore sensors in order to generate the signal.

The processor of the measurement unit will also be associated with amemory circuitry which may consist of one or more types of permanent andtemporary data storage, such as for providing the analysis on sensordata and/or calibration. In some examples, a calibration process may beperformed. For example, if two cables are to be measured, each with thesame diameter, each cable may be calibrated independently if accuracy iscritical.

The memory can be configured to store calibration parameters for avariety of unique cable sizes and/or types (e.g., cable material types,tension thresholds, storing measurements, error logs, etc.). Thehistorical measurement data can correspond to, for example, operationalparameters, sensor data, a user input, as well as data related to trendanalysis, threshold tension values, profiles associated with aparticular measurement process and/or cable type, etc., and can bestored in a comparison chart, list, library, etc., accessible to theprocessor. The output from the processor can be displayed graphically,such as the current tension measurement, a historical comparison,desired tension value, for instance.

As shown in FIG. 4, the sheave 10 is secured to the adjustable support36 by a bolt 26 that extends through the first opening 16 as well as oneor more corresponding slots of the adjustable support 36. The sheave 10is configured to rotate about the bolt 26, such that a removable pin 27can be inserted into a first slot(s) 28 or a second slot(s) 29 of theadjustable support 36. For example, when the removable pin 27 extendsthrough the first slot 28 and the second opening 18, the first diameter12 is oriented outwardly (i.e. toward the cable). Alternatively, whenthe removable pin 27 extends through the second slot 29 and the secondopening 18, the second diameter 14 would be oriented toward the cable.

The tensioners 30 are mounted on risers or arms 31 and arranged relativeto the base 32 such that, when the adjustable arm 36 is rotated aboutthe fulcrum 38 during a measurement process, the cable engages with boththe sheave 10 and the tensioners to result in a contact force. Thecontact force can be measured by a tension sensor and, via themeasurement unit 34, the tension force in the cable can be determined.The tensioners 30 can be pulleys that rotate freely during themeasurement process to eliminate or reduce friction while facilitatingengagement with the cable. In some examples, the tensioners 30 can beremovable, such that a tensioner having a groove diameter that matchesthe selected diameter of the sheave 10 (e.g., the first or seconddiameter) is in contact with the cable.

A measurement process is shown in three stages in FIGS. 5A-5C thatillustrate the tension system engaging the sheave 10 with a cable 42. Asshown in FIG. 5A, the adjustable arm 36 is open. This allows an operatorto arrange the cable 42 between the tensioners 30 and the sheave 10.FIG. 5B shows a narrowing of the gap between the sheave 10 and the cable42 as the two make contact. As the adjustable support 36 is rotatedabout the fulcrum 38, the sheave 10 slides into place against the cable42, causing the contact force on the sheave 10 in a closed position, asshown in FIG. 5c .

Thus, as shown in FIG. 5C, the contact force caused by the sheave 10forces the cable 42 away from the base 32, whereas the tensioners 30force the cable 42 toward the base 32. This balance of forces ismeasurable by the one or more sensors (e.g., mechanical, torsional,optical, magnetic, etc.), and analyzed and computed by the measurementunit 34 for presentation to the operator.

Although illustrated as rotating about an axis to force contact betweenthe sheave 10 and the wire 42, the adjustable support may be configuredas a movable arm on a vertical guide. For example, the adjustablesupport may be fixed at the based in an adjustable position by afastener (e.g., a screw, clip, tensioner, etc.). The fastener can beremoved or loosened to allow for a change in position of the adjustablesupport and/or to reorient the sheave. Once in position to contact thecable 42, the fastener can be used to fix the position of the adjustablesupport during a measurement process.

FIG. 6 shows a tension measurement system where the first diameter 12 ofthe sheave 10 is engaged with the cable 42, as shown in FIG. 5C. Forinstance, the removable pin 27 is inserted into first slot 28, therebyorienting the first diameter 12 toward the cable 42. By contrast, thetension measurement system of FIG. 7 shows the removable pin 27 insertedinto second slot 29, orienting the second diameter 14 toward cable 44.In this example, cable 44 has a diameter that is greater than cable 42.Accordingly, operating the tension measurement system with the seconddiameter 14 presented to the cable 44 provides for a more accurate cabletension measurement.

In some examples, a sheave can provide groove patterns on an arcedsurface (e.g., arc 20, 22). For instance, the arc may include striationsthat represent strands of a braided wire. In this example, the cable maymore tightly fit within the diameter of the sheave, providing moreaccurate readings during a measurement process. In the magnified view46, the cable 42 is made of fewer strands than cable 44. Thus, thecontours of the strands of cable 42 will have a different character thanthat of cable 42, as shown in magnified view 48.

As utilized herein, “and/or” means any one or more of the items in thelist joined by “and/or”. As an example, “x and/or y” means any elementof the three-element set {(x), (y), (x, y)}. In other words, “x and/ory” means “one or both of x and y”. As another example, “x, y, and/or z”means any element of the seven-element set {(x), (y), (z), (x, y), (x,z), (y, z), (x, y, z)}. In other words, “x, y and/or z” means “one ormore of x, y and z”. As utilized herein, the term “exemplary” meansserving as a non-limiting example, instance, or illustration. Asutilized herein, the terms “e.g.,” and “for example” set off lists ofone or more non-limiting examples, instances, or illustrations.

While the present method and/or system has been described with referenceto certain implementations, it will be understood by those skilled inthe art that various changes may be made and equivalents may besubstituted without departing from the scope of the present methodand/or system. For example, block and/or components of disclosedexamples may be combined, divided, re-arranged, and/or otherwisemodified. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the presentdisclosure without departing from its scope. Therefore, the presentmethod and/or system are not limited to the particular implementationsdisclosed. Instead, the present method and/or system will include allimplementations falling within the scope of the appended claims, bothliterally and under the doctrine of equivalents.

1. A sheave for use in a tension measurement system to measure a tensionforce in a cable, the sheave comprising a first diameter and a seconddiameter, the sheave configured to rotate about an axis to orient thefirst diameter or the second diameter toward the cable, wherein acontact force between the sheave and the cable is measured by a tensionsensor to determine the tension force in the cable.
 2. The sheave ofclaim 1, wherein the first diameter is arranged at a first radialposition spanning a first arc length, and the second diameter isarranged at a second radial position spanning a second arc length. 3.The sheave of claim 2, further comprising a third diameter arranged at athird radial position spanning a third arc length.
 4. The sheave ofclaim 1, wherein the orientation of the sheave is fixed relative to thecable during a measurement process.
 5. The sheave of claim 1, wherein aninterior portion of one of the first diameter or the second diametercomprises a plurality of grooves to accommodate a plurality of strandsassociated with the cable.
 6. A tension measurement system for measuringa tension force in a cable comprising: a sheave comprising a firstdiameter and a second diameter, the sheave configured to rotate about anaxis to orient the first diameter or the second diameter toward thecable; an adjustable support configured to adjust a position of thesheave relative to the cable; and a tension sensor to measure thetension force in the cable based on a contact force between the sheaveand the cable.
 7. The tension measurement system of claim 6, furthercomprising a base, wherein the adjustable support is configured torotate about a fulcrum located on the base to adjust the position of thesheave.
 8. The tension measurement system of claim 7, further comprisinga plurality of tensioners configured to engage with the cable to providethe contact force between the sheave and the cable when the adjustablesupport positions the sheave adjacent to the cable.
 9. The tensionmeasurement system of claim 8, wherein the sheave is arranged betweentwo tensioners of the plurality of tensioners along a length of thecable.
 10. The tension measurement system of claim 9, wherein the sheaveis arranged on a surface of the cable opposite the two tensioners. 11.The tension measurement system of claim 8, wherein a position of one ormore of the plurality of tensioners are fixed relative to the base. 12.The tension measurement system of claim 6, wherein the sheave furthercomprises: a first opening through which a fastener secures the sheaveto the adjustable arm at the axis; and a second opening that is offsetfrom the first opening and configured to accept a removable pin, whereinthe second opening is arranged to align with a first slot of theadjustable support to orient the first diameter toward the cable, and asecond slot of the adjustable support to orient the second diametertoward the cable.
 13. The tension measurement system of claim 6, whereinthe sheave further comprises: a first opening through which a fastenersecures the sheave to the adjustable arm at the axis; and a secondopening that is offset from the first opening and configured to accept aremovable pin.
 14. The tension measurement system of claim 13, whereinthe removable pin is configured to engage with a first slot or a secondslot on the adjustable support to fix the orientation of the sheaverelative to the cable.
 15. The tension measurement system of claim 6,further comprising a processor configured to: receive a signal from thetension sensor associated with the measured tension force; and generatea tension force alert for presentation to a user.
 16. A tensionmeasurement system for measuring a tension force in a cable comprising:a sheave comprising a first diameter and a second diameter, the sheaveconfigured to rotate about an axis to orient the first diameter or thesecond diameter toward the cable; an adjustable support comprising afirst end to mount the sheave and a second end to control movement ofthe first end relative to the cable; and a plurality of tensionersconfigured to engage with the cable to provide the contact force betweenthe sheave and the cable when the adjustable support positions thesheave adjacent to the cable.
 17. The tension measurement system ofclaim 16, wherein the adjustable support comprises a movable armconfigured to move to adjust a position of the sheave relative to thecable, the base, or the plurality of tensioners.
 18. The tensionmeasurement system of claim 16, wherein the adjustable support comprisesa telescoping pole to provide leverage for positioning the sheaverelative to the cable.
 19. The tension measurement system of claim 18,wherein the adjustable support further comprises a clamp configured tofix the position of the adjustable support in a desired positionrelative to the cable.
 20. The tension measurement system of claim 16,wherein the sheave comprises a non-conductive material.